1. Field of the Invention
The present invention generally relates to an entertainment system and method and, more particularly, to an entertainment system and method for use with a magnetic resonance imaging device.
2. Description of the Prior Art
In the medical field, magnetic resonance imaging (MRI) is a commonly used non-invasive technique to diagnose the medical condition of a patient. Typically, the patient is placed within a large homogeneous magnetic field and is subjected to a set of gradient fields and RF fields. The various fields are accurately controlled to cause nuclei within a selected slice of the patient to precess about an axis and to emit RF signals. These signals are then used to reconstruct an image of the slice. By varying the gradient fields, images of the patient at different slices may be captured. The separate slices can then be combined to form a complete scan of the patient.
A typical MRI device is designed to have a central bore within which the patient is inserted. This bore is fairly small and may induce claustrophobic feelings in the patient. As is known in the art, these claustrophobic feelings may be reduced or eliminated by providing the patient with some type of entertainment.
A problem with providing the patient with some type of entertainment is that very small magnetic fields generated by another device can destroy the images generated by the MRI device. Conversely, the strong fields generated by the MRI device may prevent the normal operation of certain devices, such as a cathode ray tube (CRT) or liquid display panel (LCD), within the vicinity of the MRI device. Therefore, any type of system used to entertain the patient must not generate any stray magnetic fields in the vicinity of the MRI device and should be shielded from the magnetic fields generated by the MRI device.
Despite these constraints, many types of systems have been designed to provide the patient with some entertainment thereby distracting the patient from the MRI procedure. In order to isolate the entertainment systems from the fields generated by the MRI device and to prevent any magnetic fields from effecting the MRI device, some systems pipe in video images to the patient while the patient is within the MRI device. For instance, U.S. Pat. No. 4,901,141 to Costello and U.S. Pat. No. 5,134,373 to Tsuruno et al. both disclose video systems in which video images are supplied through optic fibers to the patient. These systems are rather expensive to install since the MRI device must be retro-fitted with the optical fibers.
Rather than routing the video images by optical fiber, another type of entertainment system generates an image behind the MRI device and has a mirror for reflecting the image to the patient. For instance, a viewing system in U.S. Pat. No. 5,076,275 to Bechor et al. and an MRI video system disclosed in a Nuclear Associates brochure both reflect images generated from a display panel located behind the patient into the eyes of the patient. These systems may use a reflective surface mounted to the MRI device or reflective surfaces which are mounted onto goggles worn by the patient.
While these systems are easier to install than systems which route the video images through optical fibers, these systems do not readily accommodate different positions of the patient. For instance, while a patient is often in a supine position, the MRI procedures vary in whether the patient is placed in a supine position or prone position or whether the patient is placed head-first or feet-first within the MRI device. The conventional entertainment systems cannot accommodate all of the different positions that a patient may be placed and, at most, may be able to accommodate only a single position of the patient. It is therefore a problem with conventional entertainment systems which are used with MRI devices to provide video images to the patient for a variety of positions.
Also, with many of the existing MRI entertainment systems, the patient may find it difficult to focus on the video images and may therefore find it difficult to completely relax. This may be especially true for the entertainment systems which reflect the video images from behind the MRI device to the patient. With this type of entertainment system, the patient may be distracted by items which are adjacent to the display screen or by people working behind the patient. It would therefore be desirable to have the patient focus on the video images during the MRI procedure so that the patient is able to relax.
In order for the MRI device to produce high resolution images of the patient, the patient must remain as still as possible while the MRI device is operating. While the entire procedure may last more than an hour in duration, the MRI device is not imaging during the entire hour. Instead, the procedure is usually comprised of two or more imaging sequences with pauses in between the sequences. During these pauses between sequences, the patient can relax and may move about a minimal amount.
The status of the MRI procedure, such as when the MRI device is imaging or pausing, may be indicated to the patient in a variety of ways. One manner of indicating the states of the MRI procedure is by simply verbally informing the patient of whether the MRI device is imaging, pausing, or about to image. A better way, disclosed in JP-A-145643, is to flash a colored light to warn the patient that an imaging sequence is about to begin and to steadily illuminate the MRI device with the colored light for the period during which the MRI device is imaging.
A still better way, disclosed in U.S. Pat. No. 5,355,885 to Tsuda et al., provides the patient with information about the particular operation that is occurring. With the system disclosed by Tsuda et al., the inspection space within the MRI device is illuminated with a number of colors to indicate the different operations. This system illuminates the inspection space with a mixture of green and yellow light and then illuminates the space with just a yellow light during a pretreatment period. A red light flashes before the beginning of an imaging sequence and then the green light illuminates the space during the imaging sequence. As the imaging sequence progresses, the space is illuminated with a mixture of both green and yellow lights with the mixture slowly changing to entirely yellow to indicate the end of the imaging sequence. As with the beginning of the MRI procedure, the end of the entire procedure is indicated with the mixture of green and yellow lights.
While the system disclosed in Tsuda et al. can indicate the various states of the MRI device, it may be difficult for many patients to determine the exact state of the MRI device. The patient may be in a state of anxiety and may not remember the exact relationship between the colors and the states of the MRI device. Also, many patients may have trouble distinguishing a slight mixture of colors, such as green and yellow, from a pure color of light, such as just yellow. Consequently, some patients may determine that the MRI device is pausing when in fact the MRI device is still acquiring images. It is therefore a problem to accurately and reliably indicate the various states of the MRI procedure to a patient.